- General Electric Computer Accessories User Manual

GEH-6385 Reference and Troubleshooting, 2300 V Drives Chapter 3 Paramters/Functions •
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• 3-89
Speed Reference Functions
Critical Speed Avoidance
The Critical Speed Avoidance function prevents the speed reference from entering
speed avoidance zones. The user can specify three positive and three negative speed
avoidance zones. The Critical Speed Avoidance function operates on the pre-ramp
speed reference.
Function inputs
The following table specifies the input variables of the Critical Speed Avoidance
function.
Variable Description
Speed avd func input Speed reference which is the output of the Minimum
Speed Limit function (variable Min speed output). RPM
Function outputs
The following table specifies the output variables of the Critical Speed Avoidance
function.
Variable Description
Spd avd func output
Speed reference which has been prohibited from
entering the speed avoidance zones and which is the
input to the Speed Reference Ramp function (variable
Speed ref, pre ramp). RPM
Function configuration
The following table specifies the configuration parameters of the Critical Speed
Avoidance function.
Parameter Description
Crit speed avoidance Enables the Critical Speed Avoidance function.
Critical speed 1 Speed at center of speed avoidance zone 1. RPM
Critical speed 2 Speed at center of speed avoidance zone 2. RPM
Critical speed 3 Speed at center of speed avoidance zone 3. RPM
Critical speed hys
Width of speed avoidance zones on either side of center
speeds. RPM
Function description
The Critical Speed Avoidance function is part of the Speed Reference Generation
function. It operates on the speed reference after the Minimum Speed Limit function
and before the Speed Reference Ramp function. The Critical Speed Avoidance and
Minimum Speed Limit functions are coordinated so that the output of the Critical
Speed Avoidance function is outside the boundary imposed by the Minimum Speed
Limit function.
The Critical Speed Avoidance function prevents the speed reference from entering
speed avoidance zones. Each speed avoidance zone is defined by a center speed and
a hysteresis level. The user can specify three positive and three negative speed
avoidance zones.